Protein isolates from plant origin represent a valuable alternative or supplement to animal proteins in foods or feeds. For instance in foods, addition of plant proteins can effectively replace animal proteins, often at lower cost. In addition, many products traditionally containing animal proteins, in particular dairy products, may be a major cause of food allergies.
Leguminosae are notable in that most of them have symbiotic nitrogen-fixing bacteria in structures called root nodules. This arrangement means that the root nodules are sources of nitrogen for leguminosae, making them relatively rich in plant proteins. All proteins contain nitrogenous amino acids. Nitrogen is therefore a necessary ingredient in the production of proteins. Hence, leguminosae are among the best sources of plant protein. As leguminosae, such as peas (Pisum sativum), besides having a high protein content, are readily available and have a particularly well balanced amino acid composition, these represent a protein source which is a valuable alternative for animal proteins.
Major challenges in providing plant proteins revolve around protein composition and purity, and include aspects relating to for instance extraction, fractionation, and pre- and post-isolation treatments. By the time the plant protein is isolated and available in a more or less pure form, all prior manipulations have a large impact on the quality of the isolated plant protein. For instance, the type and quantity of impurities in protein isolates or extracts determine its final value. Such impurities include for instance carbohydrates. For instance leguminosae contain a significant portion of so-called flatulent sugars (e.g. raffinose, stachyose, and verbascose), which are particularly undesirable. While in general carbohydrates are unwanted impurities in the final protein isolate, some other impurities, such as vitamins or minerals may not per definition be undesirable, or may even be beneficial for nutritional and/or physicochemical aspects of the protein isolate. In addition to impacting on the final composition of the protein isolates or extracts, the extraction and/or purification process may dramatically impact on the physicochemical or functional properties of the protein isolate. In particular protein solubility, viscosity, emulsifying capacity, color, taste, or smell are heavily influenced by the used techniques.
As can be appreciated from the above, obtaining a high quality protein isolate having specific desired properties can be cumbersome, and often involves multiple expensive and/or time consuming manipulations. In view hereof, there is still a need to improve protein isolation from plants, in particular leguminosae, such as pea.
It is accordingly one of the objects of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.